This application addresses Challenge Area (04) Clinical Research and specific Challenge Topic 04-HL-114: Using existing datasets to plan effectiveness trials in pediatric cardiology. Most of the treatments used in children undergoing congenital heart surgery are not evidence-based. Treatment decisions are instead usually based on small observational studies, extrapolation from adult data, or clinician experience. We propose to link two rich data sources: The Society of Thoracic Surgeons Congenital Heart Surgery (STS-CHS) Database, which contains detailed clinical, diagnostic, operative, and outcomes data for children undergoing heart surgery, and the Pediatric Health Information System (PHIS) Database, which contains detailed information on medication utilization in children's hospitals. The linked data will include information on over 45,000 patients from 29 centers, which will be utilized to assess current variations in peri-operative treatment, and evaluate comparative effectiveness and safety of medications used in the peri-operative setting. This application will focus on investigating medications in 3 therapeutic areas: anti-fibrinolytic agents used during surgery, afterload reduction in the post-operative setting, and peri-operative antibiotic prophylaxis. Our overall hypothesis is that the linking and analysis of existing large pediatric data sources can address many of these current knowledge gaps and provide robust data in 3 specific areas: 1) identifying current practice patterns and variation in peri-operative care of children undergoing congenital heart surgery;2) performing observational comparative effectiveness studies which will provide data on efficacy and safety, as well as sample sizes, event rates, and drug effect to be used in planning subsequent trials;4) establishing a network of sites willing to participate in subsequent studies. Our research team has extensive experience in the analysis and linkage of large-scale clinical and administrative datasets and in conducting pediatric trials, and is uniquely suited to conduct the proposed study. PUBLIC HEALTH RELEVANCE: Congenital heart defects are the most common birth defects and cause a large health burden resulting in >100,00 years of life lost each year and an estimated 6 billion dollars annually in acute care costs alone. However, most medications used to treat children with congenital heart disease have not been tested in them. We propose to link two rich data sources: The Society of Thoracic Surgeons Congenital Heart Surgery Database and the Pediatric Health Information System Database to evaluate the comparative effectiveness of medications used in children undergoing heart surgery and to plan future studies to benefit children with heart disease.